Core muscle activation during dynamic upper limb exercises in women.

Although several everyday functions and sporting activities demand controlled use of the abdominal and back muscles while working with the upper limbs, the activity of core muscles during dynamic upper limb exercises in the standing position has not been studied extensively. The purpose of this cross-sectional study was to examine abdominal and back muscle activity during dynamic upper limb exercises while standing and to evaluate whether dynamic exercises are appropriate for strengthening muscles. The activation of the rectus abdominis, obliquus externus abdominis, longissimus, and multifidus muscles during dynamic bilateral or unilateral shoulder exercises with or without fixation of the pelvis was measured in 20 healthy women using surface electromyography. Trunk muscle activation during isometric maximum contraction was used as a comparative reference. With bilateral shoulder extension and unilateral shoulder horizontal adduction, abdominal muscle activity was >60% of activity during reference exercises. With unilateral shoulder horizontal abduction and shoulder extension exercises, back muscle activity was >60% of the activity level reference exercise. Muscle activation levels were 35-64% lower during shoulder horizontal adduction and abduction without fixation compared with exercises with fixation. The results indicate that upper limb exercises performed in the standing position are effective for activating core muscles. Bilateral and unilateral shoulder extension and unilateral shoulder horizontal abduction and adduction with the pelvis fixed elicited the greatest activity of the core muscles.

Effect of neck strength training on health-related quality of life in females with chronic neck pain: a randomized controlled 1-year follow-up study.

BACKGROUND: Chronic neck pain is a common condition associated not only with a decrease in neck muscle strength, but also with decrease in health-related quality of life (HRQoL). While neck strength training has been shown to be effective in improving neck muscle strength and reducing neck pain, HRQoL among patients with neck pain has been reported as an outcome in only two short-term exercise intervention studies. Thus, reports on the influence of a long-term neck strength training intervention on HRQoL among patients with chronic neck pain have been lacking. This study reports the effect of one-year neck strength training on HRQoL in females with chronic neck pain. METHODS: One hundred eighty female office workers, 25 to 53 years of age, with chronic neck pain were randomized to a strength training group (STG, n = 60), endurance training group (ETG, n = 60) or control group (CG, n = 60). The STG performed high-intensity isometric neck strengthening exercises with an elastic band while the ETG performed lighter dynamic neck muscle training. The CG received a single session of guidance on stretching exercises. HRQoL was assessed using the generic 15D questionnaire at baseline and after 12 months. Statistical comparisons among the groups were performed using bootstrap-type analysis of covariance (ANCOVA) with baseline values as covariates. Effect sizes were calculated using the Cohen method for paired samples. RESULTS: Training led to statistically significant improvement in the 15D total scores for both training groups, whereas no changes occurred for the control group (P = 0.012, between groups). The STG improved significantly in five of 15 dimensions, while the ETG improved significantly in two dimensions. Effect size (and 95% confidence intervals) for the 15D total score was 0.39 (0.13 to 0.72) for the STG, 0.37 (0.08 to 0.67) for the ETG, and -0.06 (-0.25 to 0.15) for the CG. CONCLUSIONS: One year of either strength or endurance training seemed to moderately enhance the HRQoL. Neck and upper body training can be recommended to improve HRQoL of females with neck pain if they are motivated for long-term regular exercise. TRIAL REGISTRATION: ClinicalTrials.gov NCT01057836.

Comparison of active, manual, and instrumental straight leg raise in measuring hamstring extensibility.

The active manual straight leg raise (ASLR) and passive manual straight leg raise (MSLR) tests are commonly used in clinical settings to assess hamstring tightness. However, to our knowledge, the validity and sensitivity of these tests have not been compared with the instrumental straight leg raise (ISLR). The aim of the present study was to assess the intrarater reproducibility of the ISLR and compare the sensitivity of the ASLR, MSLR, and ISLR to change. Twelve men with hamstring tightness underwent the ASLR, MSLR, and ISLR tests at baseline and after a 4-week home-based right leg stretching program with the left leg serving as a control. The ISLR measurements were repeated consecutively at baseline to assess reproducibility. The intraclass correlation coefficient for the ISLR was 0.94, and the coefficient of reproducibility was 6. Significant differences in the range of motion emerged between all testing methods (p < 0.05). In the stretched legs, the mean +/- SD increases were 17 +/- 5 degrees for ISLR, 10 +/- 8 degrees for ASLR, and 6 +/- 5 degrees for MSLR, whereas the control legs showed a significant mean change only for ASLR (5 +/- 4 degrees ). The mean standard response with the ASLR and MSLR tests did not differentiate between the treated and control legs, but it was almost 10-fold higher in the treated leg than the control leg for the ISLR, clearly differentiating between them. The ISLR had good reproducibility and sensitivity to changes, whereas ASLR and MSLR showed a poor ability to detect changes. Thus, the ISLR test is recommended for use in research evaluating the effectiveness of stretching.

Quantifying the effect of age on passive range of motion of the cervical spine in healthy working-age women.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To assess age-related changes and determine reference values for passive range of motion of the cervical spine in healthy women of working age. BACKGROUND: Although cervical mobility is age dependent, the amount in which aging affects passive range of motion has not been previously reported. It is clinically important to know the effect of normal aging process on cervical motion to be able to separate and evaluate the possible effect of pathological processes. METHODS AND MEASURES: Two hundred twenty healthy women, aged 20 to 59 years, participated in the study. Passive range of motion of the cervical spine in flexion, extension, lateral flexion, and axial rotation was measured with the Cervical Measurement System. Measurements to calculate intrarater reliability were obtained on 22 subjects. RESULTS: Passive range of motion of the cervical spine diminished linearly with increasing age in all measured movement planes (P<.001 for all movements except for flexion which was P = .018). Mean body mass index adjusted reduction in passive range of motion was 0.5 degrees per 1-year increase in age. Intraclass correlation coefficients for intrarater reliability ranged from 0.79 to 0.92. CONCLUSION: A gradual age-related reduction in passive cervical range of motion was observed in women of working age.

Effect of isometric upper-extremity exercises on the activation of core stabilizing muscles.

OBJECTIVE: To evaluate whether isometric exercises for the upper extremities could sufficiently activate core stabilizing muscles to increase muscle strength. DESIGN: Cross-sectional study. SETTING: Department of physical medicine and rehabilitation at a Finnish hospital. PARTICIPANTS: Healthy adult women (N=20). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak isometric strength of the back and abdominal muscles was measured and relative loading in 5 test exercises was evaluated by surface electromyography. RESULTS: The rectus abdominis and obliquus externus abdominis were activated to the greatest degree in a bilateral shoulder extension exercise and the average surface electromyographic activity was 114% and 101% compared with the amplitude elicited during the maximal isometric trunk flexion exercise. Horizontal shoulder extension elicited the greatest activation of the longissimus and multifidus muscles. In this exercise, the activity levels of the left side multifidus and longissimus muscles were 84% and 69%, respectively, compared with the level of activity elicited during trunk extension. CONCLUSIONS: Of all the exercises studied, bilaterally performed isometric shoulder extension and unilaterally performed horizontal shoulder extension elicited the greatest levels of activation of the trunk musculature. Thus, it can be assumed that these exercises elicit sufficient levels of contraction of the trunk muscles for the development of their endurance and strength characteristics in rehabilitation.

Force production and EMG activity of neck muscles in adolescent headache.

PURPOSE: This study compared the maximal force, EMG/force ratio and co-activation characteristics of the neck-shoulder muscles between 30 adolescents with migraine-type headache, 29 with tension-type headache, and 30 headache-free controls. METHOD: Force was measured with surface electromyography (EMG) from the cervical erector spinae (CES), the sternocleidomastoid (SCM) and trapezius muscles during the maximal isometric neck flexion, neck extension and shoulder flexion. RESULTS: Girls with migraine-type headache had higher EMG/force ratios between the EMG of the left agonist SCM muscle and the corresponding maximal neck flexion (p = 0.030) and neck rotation force to the right side (p = 0.024) than the girls with tension-type headache. Migrainous girls had more co-activation of right antagonist CES muscle during maximal neck flexion force than the girls without headache (p = 0.015). Neck force production showed no significant differences between girls. Girls with tension-type headache displayed lower left shoulder flexion force than girls with migraine-type headache (p = 0.005) or with no headache (p = 0.005). In boys, no significant differences were observed. CONCLUSIONS: Girls with tension-type headache and migraine-type headache have differences in neuromuscular function in the neck-shoulder muscles. The data amplify our knowledge of the neck-shoulder muscle dysfunction in adolescent headache, and may encourage the use of specific rehabilitation methods in the management of different types of headache.

Repeatability of electromyography and force measurements of the neck muscles in adolescents with and without headache.

BACKGROUND: Reliable measurements are needed to study the dysfunction of the neck muscles. The aim of this study was to determine the intra-tester repeatability of EMG and isometric force measurements of the neck muscles in adolescents with headache and headache-free controls. METHODS: A group of 30 adolescents with migraine-type headache, 29 with tension-type headache, and 30 headache-free controls were recruited. Maximal isometric neck muscle force with simultaneous recording of surface EMG from the cervical erector spinae and the sternocleidomastoideus muscles was measured twice during one day. FINDINGS: For all groups, intra-class correlation coefficients (ICC) and coefficients of variation (CV) showed acceptable repeatability of all measurements. (Force measurements: ICC 0.98-0.99, CV 0.7-3.7%; EMG measurements: ICC 0.95-0.99, CV 4.9-10.1%.) On the individual level, variation between the consecutive measurements was found to be low in all groups. INTERPRETATION: The present EMG and force measurements of neck muscles indicate acceptable intra-tester repeatability in adolescents. The repeatability was comparable in migraine- and tension-type headache and headache-free groups. The EMG and the force measurements offer the possibility to investigate neck muscle dysfunction in adolescent headache.

Isometric strength of the cervical flexor, extensor, and rotator muscles in 220 healthy females aged 20 to 59 years.

STUDY DESIGN: Cross-sectional descriptive study. OBJECTIVES: To determine the maximal isometric strength of the flexor, extensor, and rotator muscles of the cervical spine in healthy females of working age to document reference values for diagnostic and rehabilitation purposes. BACKGROUND: Reference values for the isometric strength of the cervical muscles have often been based on small samples. To date, reference values for rotator muscles of the cervical spine have not been published. METHODS AND MEASURES: The group consisted of 220 volunteer healthy females in 4 age groups (20-29 years, n = 57; 30-39 years, n = 51; 40-49 years, n = 51; 50-59 years, n = 61) from Jyadskyla, Finland. Isometric cervical muscle strength in flexion, extension, and rotation was evaluated with a specially designed measurement system. RESULTS: Across all age groups, mean (+/-SD) maximal isometric neck strength was 73.8 +/- 20.0 N in flexion and 190.8 +/- 31.3 N in extension. Mean (+/-SD) rotation strength was 8.1 +/- 2.3 Nm to the right and 7.9 +/- 2.3 Nm to the left. Absolute strength values did not differ among the age groups. A weak but significant correlation between body mass and neck flexion (r = 0.31, P<.01) and extension (r = 0.25, P<.01) strength was found. Intratester reliability varied from 0.87 to 0.96. CONCLUSIONS: Women aged 20 to 59 years appear to have similar absolute isometric neck muscle strength levels. Thus these values can be used as reference for the working-age female population.

Effects of twelve-month strength training subsequent to twelve-month stretching exercise in treatment of chronic neck pain.

Previously, in a randomized study, we showed that women with chronic neck pain were able to perform intensive training for neck and shoulder muscles and that the increase in strength was accompanied by a reduction in pain and disability. The changes were significantly greater in the training groups compared with controls. The aim of the present study was to evaluate whether the controls would achieve similar results. Thus, 59 women in the control group initiated high-intensity strength training. Maximal isometric neck strength increased by 44% in both flexion and rotation and 27% in extension at the 2-year follow-up. Statistically and also clinically significant decreases in neck pain and disability indices occurred. Stretching and aerobic exercising during the first follow-up year produced only minor changes in both subjective and functional measures. Adding progressive strength training for the second year led to a significant improvement in neck strength and also to a considerable decrease in the pain and disability scores. Thus, to achieve effective rehabilitation in cases of chronic neck pain, a combination of strength training and stretching exercises are recommended.

Effects of neck muscle training in women with chronic neck pain: one-year follow-up study.

Exercises are commonly recommended for chronic neck pain, but evidence-based guidelines do not explain what types of exercise. The aim of this randomized study was to evaluate the rate of change in neck strength following high- and low-intensity neck muscle training and their effects on pain and disability. One hundred eighty women with chronic neck pain were randomized into a high-intensity strength training group (STG), local muscle endurance training group (ETG), or control group (CG). The neck training consisted of isometric exercises in the STG and dynamic exercises in the ETG. Both groups performed dynamic exercises for the upper extremities. Strength tests, neck pain, and disability indices were evaluated at the baseline, at the follow-ups after 2 and 6 months in the training groups, and after 12 months in all groups. In both groups the greatest gains in neck strength, as well as decrease in neck pain and disability, were achieved during the first 2 months. However, the improvements continued up to 12 months. The STG achieved the greatest strength gains at all follow-ups. The CG showed only minor changes, and significant differences were found in favor of the training groups in all measures. The change in neck pain and disability indices correlated with the isometric neck strength (r = -0.22 [-0.36 to - 0.08] to -0.36 [-0.49 to -0.23]). Neck and shoulder muscle training was shown to be an effective therapy for chronic neck pain, resulting in early improvement in both the strength tests and subjective measures. The results can be maintained and even improved with long-term training.

Effect of training in Greco-Roman wrestling on neck strength at the elite level.

Special training methods in wrestling have been assumed to improve the stability and tolerance of the neck. The aim of this study was to measure the neck strength levels reached in an extremely physically demanding sport. A neck strength measurement system was used to measure various parameters of maximal isometric neck strength in Finnish senior wrestlers competing at the international level. The results were compared with those achieved by junior wrestlers and a control group. The means (SD) of the maximal isometric neck strength for cervical rotation were 0.4 (0.1) Nm.kg(-1) for the senior wrestlers, 0.3 (0.1) Nm.kg(-1) for the junior wrestlers, and 0.2 (0.1) Nm.kg(-1) for the nonsportsmen. The respective results for cervical flexion were 4.4 (1.4), 3.8 (0.7), and 2.3 (0.8) Nm.kg(-1); for extension, 6.0 (1.1), 5.9 (0.7), and 4.0 (0.9) Nm.kg(-1). Neck strength in flexion seems to improve more than in extension as the result of wrestling. The greatest difference was found in rotation, which in the senior wrestlers was almost 3 times that in the nonsportsmen. There was great individual variation within all groups, and the results revealed weaknesses in all directions. Maximal neck strength measurements provide information useful in planning training programs to correct possible muscle deficiency and imbalance.

Decreased strength and mobility in patients after anterior cervical diskectomy compared with healthy subjects.

OBJECTIVE: To evaluate whether patients acquired normal physical function after cervical disk prolapse and surgery compared with healthy matched controls. DESIGN: Cross-sectional study. SETTING: Hospital in central Finland. PARTICIPANTS: Fifty-three patients with cervical diskectomy and 53 healthy matched controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Postoperative physical function was studied by measuring muscle strength and range of motion (ROM) values of the neck and grip strength. Disability was assessed by the neck and shoulder pain index and by the Oswestry index, mood by the Short Depression Inventory; and pain on a visual analog scale (VAS). RESULTS: Most patients recovered well after the operation. Forty-three percent of the patients still experienced moderate or high pain (VAS score, >30mm). Subjective pain and disability were associated with decreased neck movement and strength. Both ROM and cervical muscle strength values were significantly lower (P<.001) in all the measured directions in cervical disk surgery patients compared with healthy controls. ROM was mostly confined in extension (25%). Muscle strength of the neck was mostly confined in both rotation directions (38%). No statistically significant difference in grip strength was found between the groups. CONCLUSION: The loss of muscle strength and ROM is clearly visible postoperatively and thus the effectiveness of the early identification and rehabilitation of these deficits merits further studies.